Quick start and stop drive mechanism for phonograph turntables



L. THOMPSON Apr 7, 1942.

QUICK START AND STOP DRIVE MECHANISM FOR PHONOGRAPH TURNTABLES .Filed April 10, 1941 I5 37 3s H I 3 36 a 4 I6 35 a a; 34 3o 32 I! i l '4 33 '31 MF'UFIER INVENTOR Luzcaln Thampsmz ATTORNEY Patented Apr. 7, 1942 UNITED STATES PATENT OFFICE QUICK START AND STOP DRIVE MECHA- NISM FOR PHONOGRAPH TURNTABLES Lincoln Thompson, Cheshire, Conn., assignor to to The Soundscriber.Corporation, New Haven,

Conn., a corporation of Connecticut Application April 10, 1941, Serial No. 387,893

post I2, is adapted to be-supported on the turn- Claims.

' This invention relates to phonograph machines for transcribing. records of the disc type, and more particularly to a mechanism for driving the record supporting turntable, together with means for permitting said turntable to be quickly started and stopped.

One object of this invention is to provide an improved start and stop mechanism of the above nature which will include a light low-inertia turntable, a heavy motor-operated driving plate, and a friction slip clutch ring located therebetween.

A further object is to provide a device of the above nature which will be simple in construction, inexpensive to manufacture, easy to install and manipulate, compact, ornamental in appearance,

and very eflicient and durable in use.

With these and other objects in view, there has been illustrated in the accompanying drawing two forms in whichthe invention may be conveniently embodied in practice.

In the drawing:

Fig. 1 is a schematic view of the inventio showing in cross-section the record supporting turntable in cooperating relation with driving and braking'means therefor, and-showing diagrammatically the remainder of the apparatus and electrical control circuits.

Fig. 2 is a top plan view of the record-supporting turntable.

Fig. 3 is a diagrammatic view of a modified form of the invention.

This invention is an improvement over that disclosed in applicant's ,copending application, Serial No. 242,598, filed November 26, 1938, entitled Quick start and stop mechanism for phonograph turntable," patented April 29, 1941, No. 2,240,320.

The present invention is of particular importance for use in the transcriber of a disc type dictating machine for it enables the record to be started and stopped with extreme rapidity without stopping the motor, which runs continuously. It-

l3, preferably of aluminum, having a square opening at its center to fit over and be centered by the table ID in position to have its sound grooves engaged by the needle 14 of an electrical pick-up member 15. The pick-up member is adapted to swing freely across the record 13 and is connected by conductors I6 and I1 to an audion amplifier l8 for operating a loudspeaker, or other sound producing device l9, which is connected to' said amplifier by conductors and 2|. Electrical energy may be supplied to the amplifier 18 from line wires LI and L2 b conductors 22 and 23 leading to a separable plug and socket 24 and A continuously running motor 25 is operably connected to a vertical shaft 21 by means of a flexible coupling 28. The shaft 21 extends upwardly through a bearing 29 rigidly mounted in the machine frame and has a relatively heavy thick circular driving disc, or plate30, secured thereto by a set screw 30a. The driving plate 30 has its top outer surface cut away to provide a vertical annular shoulder 3| about which a narrow ring 32 of friction material such as cork, is fitted and cemented,.said ring being of rectangular cross-section and having its upper surface raised slightly above the upper surface of the plate 30 and adapted to frictionally engage the under surface of the turntable l0.

- The shaft 21 is provided on its upper end 33 with an anti-friction collar 34, such as graphite,

which collar is surrounded by a hollow conical hub 35 formed integral with the turntable II! to form a bearing for the upper end 33 of the shaft Provision is also made of a screw 36 having an upper head 31 disposed in a-'circular counterbore 38 provided in the square post 12. The shank of 'said screw. extends downwardly from said head and is screw-threaded into the upper end 33 of the shaft 21, whereby the turntable ill will be maintained in operating position. The shank of the screw 36 is provided with a shoulder 39 which is adapted to seat against the upper end- 33 of the shaft 21.

By means of the above construction, it will be obvious that the rotation of the shaft 21 by the motor 26 will drive the turntable Ill, and the record 13 mounted thereon, by means of the frictional engagement between the narrow cork ring 32 and th undersurfaceof the turntable 10. It will also be seen that thelight-Weight turntable ,10 possesses very low inertia and may be instantly stopped by the application of a relatively small braking force to the flange thereof, ashereafter described. The plate 30 being relatively heavy in weight, and consequently possessing high inertia,

will continue to rotate without appreciable decrease in speed whenever the turntable is stopped by means of the brake, and when the, brake is instantaneously.

In order to momentarily stop the rotation of the turntable whenever desired, provision is made of a brake shoe 40, preferably made of a leather collar fitted upon the upper end of an upstanding brake rod 4| in position to engage ,frictionally against the outside surface of the depending flange ll of the turntable Ill. The brake rod 4|, in this instance, is pivotally secured to the lower arm 42 of a fixed U-shaped electromagnetic core which is adapted to b energized by current passing through a coil of wire 43, surrounding the vertical base of said core. The coil 43 is connected by a conductor 44 to one. terminalof a switch 45,

and by another conductor 46 to a current rectifier 41, the other terminal of the switch 45 being connected by a conductor 48 to said rectifier 41.

The rectifier 41 receives alternating current from a pair of conductors 49 and 50, leading to the line wires LI and L2. The upper arm 5| of the electromagnetic core is disposed adjacent the brake rod 4|, and is adapted to attract the brake rod 4| whenever the coil 43 is energized to force the brake shoe 4|] against the fiange H of theturntable It) to stop instantly the rotation of the samethe coil 43 being energized by manual closure 'of the switch 45, which may be operated by the hand or foot of the operator. A spring 52 reacting between the brake rod 4| and a, stationary post 53 is tensioned to constantly urge said brake rod 4| away from the magnet arm 5 I, so as to release the braking action of the brake shoe 40 on the-turntable In, automatically, whenever the operator releases the switch button 54 to open the circuit. The switch 45 is adapted to be automatically opened by a compression spring 55.

In themodified form of the invention shown in Fig. 3, theswitch 45 will be normally held in closed position by a spring 5541, and'is arranged to'be opened manually by depressing the push button 540. whenever it is desired to start the turntable into rotation. In each form of the invention the motor 26, the rectifier 41 and the amplifier l8 are simultaneously controlled by a manual switch 56 located in the conductor 23 leading to the plug 24. 7

It will be understood that the friction between the large diameter narrow cork ring 32 and the turntable It will be slight enough so that when the turntable I0 is stopped by the brake shoe 40,-

the motor 26 and the plate 30 will not be materially impeded, but will continue to rotate at substantially full speed. Such friction, however,

should be suflicient to insure the practically in-- stantaneous starting of the light turntable ID at full speed when the brake shoe 40 is disengaged from the turntable flange, and without being retarded by the work required to move the needle in the groove of the disc record.

It will be understood that in the operation of the modified form shown in Fig. 3, whenever the be utilized by the operator as a definite signal to indicate that the machine is then ready to start transcribing.

One advantage of the use of the present slip friction clutch ring of relatively large diameter is that it will serve to give a more stabilized sup port to the turntable, and will render the latter less likely to tip or rocl; without the use of an excessively long central spindle.

While there has been disclosed in this specification two forms in which the invention may be embodied, it is to be understood that these forms are shown for the purpose of illustration only, and that the invention is not to be limited to the specific disclosure but may be modified and embodied in various other forms without departing from its spirit. In short, the invention includes all the modifications and embodiments coming within the scope of the following claims.

Having thus fully described the invention,

what is claimed as new and for which it is desired to secure Letters Patent, is:

1. In a phonograph, a continuously rotating driving plate of high inertia, a low inertia turntable for supporting a disc record having a short flange covering said plate, a solenoid-operated brake 'rod carrying a brake shoe positioned adjacent said fiange to engage it'and stop the rotation of said turntable, a friction ring of relatively large diameter mounted on said plate for engaging the undersurface of said turntable, said ring acting as a slip-friction clutch between said plate and said turntable.

2. In a phonograph, a continuously rotating driving plate of relatively high inertia, a turntable of low inertia for supporting a disc record located above said plate, a manually operated brake rod for engaging said turntable to stop the rotation thereof, a slip-friction clutch ring carried by said plate for engaging and supporting said turntable, the friction between said ring and said plate being low enough so that the stopping of said turntable by said brake rod will not stop-the rotation of said plate; but high enough to cause said turntable to assume full -speed rotation instantly when said brake rod is released.

3. In a phonograph, a continuously rotating driving plate, a turntable of low inertia for supporting a disc record located above said plate, a manually operated brake rod for engaging said turntable to stop the rotation thereof, a narrow slip-friction clutch ring of relatively large diameter carried by said plate for engaging and supporting said turntable, the friction between said ring and said plate being small enough that the stopping of said turntable by said brake rod will not stop the rotation of said plate, but large enough to cause said turntable to assume full speed rotation instantly when said brake rod is released.

4. In a phonograph transcriber, a continuously rotating driving plate, a turntable of low inertia for supporting a disc record located above said plate, a brake rod for engaging said turntable to stop the rotation thereof, a narrow slipfriction clutch ring of rectangular cross section and relatively large diameter carried by said plate for engaging and supporting said turntable, the friction between said ring and said plate being of such magnitude that the stopping 5. In a phonograph, a continuously rotating driving plate, a turntable of low inertia for supporting a disc record located above said plate, a manually operated brake rod for engaging said turntable to stop the rotation thereof, slip-friction clutch means of relatively large diameter carried by said plate and located adjacent the periphery of said plate for engaging and supporting said turntable, the friction between said means and said plate being such that the stopping of said turntable by said brake rod will not stop the rotation of said plate, and that said turntable will resume full speed.rotation. when said brake rod is released, said means extending above the surface of said plate.

6. In a phonograph, a turntable of relatively low inertia for supporting a disc record, a continuously rotating heavy thick plate for driving said turntable, clutch carried by said plate for .engaging and supporting said turntable rigidly without tipping, said clutch being of relatively large diameter and small in area so as to have only a slight upper surface to afiord a stable fricl tional support for said turntable, a manually 0perated brake for engaging, said turntable to stop the rotation thereof, the friction between said clutch and said turntable being sufficient to cause the latter to resume full speed rotation instantly when said brake is released.

'7. In a phonograph, a continuously rotating driving plate, a turntable of low inertia for supporting a di c record located above said plate, a brake rod for engaging said turntable to stop the rotation thereof, slip-friction clutch means carried by said plate for engaging and supporting said turntable, said means being flat and of sufficient size that the stopping of said turntable by said brake rod will not stop the rotation of said plate, and yet causing said turntable to resume full speed rotation instantly when said brake rod is released, said plate havingits outer portion cut away to provide a shoulder for receiving said clutch means.

8. In a phonograph, a continuously rotating driving plate, a turntable of low intertia for supporting a ,disc record located above said plate, a brake rod for engaging said turntable to stop the rotation thereof, a narrow slip-friction clutch of relatively large diameter carried by said plate top of said shaft to hold said turntable in op erating position.

9. In a phonograph, a continuously rotating driving plate of relatively high inertia, a-turntable of relatively low inertia for supporting a disc record located above said plate, a manually operated brake rod for engaging said turntable to stop the rotation thereof, friction means car-' ried byv said plate for engaging and supporting said turntable, the friction between said means and said plate being such that the stopping of said turntable by said brake rod will not stop the rotation of said plate, and yet causing said turntable to resume full speed rotation instantly when said brake rod is released, a motor-driven shaft for driving said plate, and a headed screw connected to the top of said shaft to hold said turntable in operating position, the central part of said turntable having a'depending hub carrying a bearing bushing to embrace the top. of said shaft and centralize said turntable.

10. In a phonograph, a continuously rotating driving plate of high inertia, a low inertia turntable for supporting a disc record having a short flange covering said plate, a solenoid-operated brake rod carrying a brake shoe for engaging said flange to stop the rotation of said turntable,

a friction ring mounted on said plate for engag-c ing and supporting the undersurface of said tumtable, said ring acting as a slip-friction clutch between said plate and said turntable, a tube operated rectifier for operating said solenoid to attract said brake rod and stop the rotation of said turntable, and means to cause rotation of said turntable initially before the tubes of said rectifier heat up,the stopping of said rotation when the solenoid coil is energized after the heating ofsaid' tubes serving as a signal that the machine is ready for transcription.

LINCOLN THOMPSON. 

